Gain adjusting and circuit arrangement

ABSTRACT

The present invention relates to a method and circuit arrangement for adjusting a gain, wherein said circuit arrangement comprises at least a first output branch connected to a first load and a second output branch connected to a second load. The gain control function is realized based on a current splitting, wherein a non-operated output branch is used as a kind of dummy branch for receiving a part of the output current. Thus, only as many output branches as there are outputs are required to implement a gain control based on splitting. Thereby, a complexity of the layout design is reduced and control and biasing of dummy branches is not required.

This is a Continuation of application Ser. No. 10/476,788 filed Nov. 6,2003, now U.S. Pat. No. 6,980,051 which is a 371 application ofInternational Application PCT/EP01/05220 filed May 8, 2001. Thedisclosure of the prior application is hereby incorporated by referenceherein in its entirety.

FIELD OF THE INVENTION

The present invention relates to a gain adjusting method and circuitarrangement for performing a gain adjustment e.g. in a radio frequency(RF) part of a radio receiver, integrated circuits, or a multi-mode andmulti-band system.

BACKGROUND OF THE INVENTION

In general, mobile communication systems such as GSM (Global System forMobile Communication), GPRS (General Packet Radio Services) or UMTS(Universal Mobile Communications System) are designed to provideinternational digital cellular services. Originally, in GSM, the 900-MHzband was reserved for GSM services, wherein the frequency band from 890to 915 MHz was reserved for the uplink direction, i.e. sending data froma mobile station or terminal to a base station, and the frequency bandfrom 935 to 960 MHz was reserved for the downlink direction, i.e.sending data from the base station to the mobile station or terminal.Since GSM first entered commercial service in 1992, it has been adaptedto work at 1800 MHz for the Personal Communications Networks (PCN) inEurope and at 1900 MHz for Personal Communications Systems (PCS) in theUnited States. Accordingly, there exist three main GSM systems operatingat three different receiving frequency bands. Hence, a mobile stationcovering all these systems has to be switchable between the differentreceiving frequency bands to be operable in different areas havingdifferent GSM standards.

Conventional receiver front ends comprise multiple low-noise amplifiersand multiple mixers, wherein the number of low-noise amplifiers andmixers correspond to the number of different receiving frequency bandswhich have to be received by the mobile station. For instance, within amobile station designed to receive a broadcast signal in the downlinkfrequency bands of GSM 900, GSM 1800 and GSM 1900, three differentlow-noise amplifiers and three different mixers have to be employed.This leads to the drawback that many components have to be integratedwithin a mobile station, thus increasing its total production cost andmaking a further miniaturization difficult.

A solution to the above problem was supposed in document BP 1 006 669A1, where a wide-band low-noise amplifier is connected to a broadcastsignal receiving means in order to amplify the broadcasted signals ofall receiving frequency bands, and an amplified output signal isbranched to multiple switches of a switching means, wherein the numberof the switches corresponds to the number of receiving frequency bands.Multiple filters each connected to one of the switches are provided,each filter having a band pass filtering characteristic to pass allsignals within an associated receiving frequency band. Furthermore, amixing means is connected to the output side of each filter and arrangedto mix the filter signal with locally generated mixing signal from afrequency synthesizer to produce an intermediate frequency signal. Theswitching means is arranged to switch on one of the switches based on afirst control signal supplied from a control means so as to switch onone of the switches and thereby select one of the multiple receivingfrequency bands. A second control signal is supplied from the controlmeans to the frequency synthesizer to generate a mixing signalcorresponding to the selected receiving frequency band.

In multi-band and multi-system receivers there is usually a need fordifferent loads. The loads are usually frequency selective, e.g.resonators or the like, and are thus tuned according to the receptionfrequencies of individual systems, as mentioned above. When a gainadjustment is to be performed in the RF part of receivers, a gaincontrol circuitry can be based on current splitting, wherein dummybranches were proposed to be used to provide the current splittingfunction.

FIG. 2 shows such a gain control circuitry in a single-bandsingle-system receiver, where a part of the output current of an inputstage 10 of a low-noise amplifier is switched by a switching means 20 toa dummy branch which is connected to a supply voltage (V_(DD)). It isnoted that the dummy branch may be connected to any suitable potentialor device. The portion switched to the dummy branch can be determined orcontrolled by selecting a number of parallel switches of the switchingmeans 20, which is to be switched to the dummy branch. The remainingpart of the output current is supplied to a load Z1 and an outputterminal OUT1. The load Z1 may be a frequency selective load tuned tothe receiving frequency band of the single-band single-system receiver.However, using this kind of solution in multi-mode and multi-bandreceiver systems would require a plurality of dummy branches which leadsto an increased number of components, thus increasing production costsand size of implementation.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a gainadjusting method and circuit arrangement, by means of which a gaincontrol function can be introduced in multi-band systems at lowproduction costs and facilitated miniaturization.

This object is achieved by a method for adjusting a gain in a circuitarrangement comprising at least a first output branch connected to afirst load and a second output branch connected to a second load, themethod comprising the steps of:

providing a first operation mode in which the first output branch isoperated and the second output branch is not operated, and a secondoperation mode in which the first output branch is not operated and thesecond output branch is operated; providing a switching function forswitching a predetermined portion of the branch current of one of thefirst and second output branches to the other of the first and secondoutput branches; andadjusting the gain in at least one of the first and second operationmodes by changing the predetermined portion of the output current.

Furthermore, the above object is achieved by circuit arrangement forperforming a gain adjustment, the circuit arrangement comprising:

a first branch connected to a first load, the first branch beingoperated in a first operating mode of the circuit arrangement and beingnot operated in a second operating mode of the circuit arrangement;

a second branch connected to a second load, the second branch beingoperated in the second operating mode and being not operated in thefirst operating mode; switching means for switching a predeterminedportion of the branch current of one of the first and second outputbranches to the other one of the first and second output branches to theother one of the first and second output branches; and adjusting meansfor adjusting the gain by changing the predetermined portion.

Accordingly, the number of parallel switched branches can be reduced inmulti-band or multi-system receivers compared to typical gain adjustmentcircuits based on current splitting, since loads related tonon-operational output branches are utilized for receiving a portion ofthe output current of the operational or operated output branch. Thus,the signal current is split up into a first part directed to anoperational output branch and a second part directed to one or aplurality of the non-operational output branches. Depending on the ratiobetween the current portions, the gain of the concerned receiver circuitpart can be controlled or determined, since the effective load reflectedat the output of the circuit arrangement is changed according to theratio of the above mentioned current portions.

The adjusting step may be performed by controlling individual switchingelements of the switching function, so as to determine the predeterminedportion. In particular, the individual switching elements may becontrolled by selectively supplying a control signal to controlterminals of the individual switching elements.

The circuit arrangement may be comprised in a dual-band receiver,wherein the first operating mode is provided to receive a firstfrequency band and a second operating mode is provided to receive asecond frequency band. In this case, the first and second loads may befrequency-selective loads tuned to the first and second frequency band,respectively. The circuit arrangement may be a low-noise amplifier ofthe dual-band receiver.

Furthermore, the switching means may comprise a plurality of parallelswitching elements arranged to supply their switched current either tothe first output branch or to the second output branch. In particular,the parallel switching elements may be transistor means. Then, theadjusting means may comprise switching means for switching a controlsignal to the transistor means. The transistor means may be transistorpairs.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the present invention will be described in greaterdetail based on preferred embodiments with reference to the drawingfigures, in which:

FIG. 1 shows a schematic block diagram of a low-noise amplifieraccording to the preferred embodiments of the present invention;

FIG. 2 shows a schematic block diagram of a low-noise amplifier gainadjustment based on current steering;

FIG. 3 shows a schematic circuit diagram of a possible implementation ofthe low-noise amplifier according to a first preferred embodiment; and

FIG. 4 shows a schematic circuit diagram of another possibleimplementation of the low-noise amplifier according to a secondpreferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments will now be described on the basis of alow-noise amplifier provided in an RF part of a dual-band radioreceiver.

FIG. 1 shows a schematic block diagram of the low-noise amplifieraccording to the first preferred embodiment with two output terminalsOUT1, OUT2 and N input terminals IN1 to INN. The low-noise amplifiercomprises an input stage 10 comprising the N input terminals IN1 to INN,to which N individual input signals can be applied. The gain of thelow-noise amplifier can be adjusted by a switching stage 20 comprising aplurality of switching elements for switching respective output signalsof the input stage either to a first output branch connected to a firstload Z1 or to a second output branch connected to a second load Z2. Thefirst output branch comprises a first output terminal OUT1 foroutputting an output signal corresponding to the first output branch,and the second output branch comprises a second output terminal OUT2 foroutputting an output signal of the second output branch. In case of adual-band receiver arrangement. The first load Z1 may be a firstfrequency-selective load, e.g. a resonance circuit or the like, and thesecond load Z2 may be a second frequency-selective load, e.g. aresonance circuit or the like.

By selectively switching the switching elements of the switching stage20, the portions of the total output signal or current supplied to therespective output branches can be determined. Thereby, the effectiveloads responsible for the signal gains obtained at the output terminalsOUT1, OUT2 can be adjusted or controlled.

It is noted that the current splitting may as well be implemented as ananalogue or continuous value current splitting. In this case, in FIG. 1,all switches of the switching stage 20 except one can be removed. Theremaining switch may then be controlled in a way that the total currentis split into two predetermined portions which are supplied to therespective output branches. For example, three cases are thenpossible: 1) the total current through the switch is flowing through thefirst load Z1; 2) the current portion through the first load Z1 isdecreased and the current portion through the second load Z2 isincreased; or 3) the total current through the switch is flowing throughthe second load Z2. In this way, the signal gain of the amplifier can becontrolled in an analogue manner (no discrete steps).

Due to the fact that only one of the two output branches is operated,while the other one is not operated (e.g. based on the receivedfrequency band), the non-operated output branch can be used as a kind ofdummy load branch for the operated output branch. Thus, the requirednumber of output branches for implementing a gain adjustment functioncan be halved, which makes the layout design easier and the control andbiasing of dummy branches are not needed.

The loads Z1, Z2 of the first and second output branches may beband-pass filters with a filtering characteristic to pass signals withina downlink receiving frequency band of the respective receivingfrequency band. In particular, the loads may be resonance circuit with adiscrete capacity or inductivity, surface acoustic wave filters,dielectric filters, or other frequency-selective elements or circuits.

Furthermore, a control unit (not shown) may be provided whichautomatically detects the receiving frequency band on which data isreceived from a transmitting side, and which generates control signalssupplied to the switching stage 20 to indicate which of the outputbranches is to be operated and which is to be not operated. Furthermore,another control signal may be generated to control a local oscillatorsignal required for down-converting the frequency of the received radiosignal in accordance with the respective downlink receiving frequencyband.

By switching a part of the output signal current to the non-operationaloutput branch, the gain of the low-noise amplifier can be reduced.

FIG. 3 shows a possible implementation of the low-noise amplifiercircuit according to the first preferred embodiment. In FIG. 3, theloads Z1, Z2 of the first and second output branches are connected to asupply voltage V_(DD) and are formed by parallel resonance circuits. Theswitching stage 20 comprises an arrangement of four parallel transistorsT1 to T4 for switching a respective part of the output current of thefirst output branch and four parallel transistors T5 to T8 for switchinga respective part of the output current of the second output branch. Thefour transistors T1 to T4 allocated to the first output branch arecontrolled at their base terminals by corresponding switching elementsC1 to C3 for supplying a base control voltage V_(B1) to the baseterminals, and by switching elements C 1 to C 3 for switching a groundpotential to the base terminals. It is noted that the switching elementsC1 to C3 and C 1 to C 3 are adapted in such a manner that the switchingstate of the switching elements C 1 to C 3 is inverse or opposite to theswitching state of the switching elements C1 to C3. The same applies tothe transistors T5 to T8 allocated to the second output branch, whereinthe switching elements C 1 to C 3 are arranged to switch a base controlvoltage V_(B1) to the base terminals, and the switching elements C1 toC3 are arranged to switch ground potential to the base terminals. Thus,the states of the transistors T5 to T8 are opposite to the respectivestates of the transistors T1 to T4.

For example, if the transistor T1 is in a conducting state by closingthe switching element C1 (opening the switching element C 1), then thetransistor T8 is in a non-conducting state, since ground potential isapplied via the switching element C₁ to the base control terminal of thetransistor T8. The same applies to the other transistors.

The low-noise amplifier shown in FIG. 3 is arranged as a single-endedstructure with two inputs, where the input voltages V_(IN1) and V_(IN2)are supplied to respective input transistors T9 and T10, respectively,which are connected via corresponding inductors to ground potentials.The inductors are used for matching purposes in connection with a baseinductance (not shown) of the respective one of the transistors T9 andT10. E.g., the input impedance of the low-noise amplifier can be matchedto 50 Ω as required by a preceding pre-selection filter or duplexer.

The switching elements C1 to C3 and C 1 to C 3 of the first outputbranch and the switching elements C1 to C3 and C 1 to C 3 of the secondoutput branch may be chemically or electronically coupled to ensuresynchronism and equal switching states.

Thus, depending on the switching state of the switching elements of C1to C3 and C 1 to C 3, which may be controlled by supplying binarycontrol signals to corresponding electronical or logical switchingelements, the state of the transistors T1 to T8 can be controlled.Thereby, the output current of the low-noise amplifier can bedistributed in a predetermined ratio to the two output branches, tothereby determine and adjust the gain of the operational output branch.E.g., if all transistors T1 to T4 are switched on, which correponds to aclosed switch, the maximum output current is supplied to the firstoutput branch and thus to the load Z1. On the other hand, if alltransistors T5 to T8 are switched on, i.e. switch closed, the maximumoutput current is supplied to the second output branch and the secondload Z2.

As already mentioned in connection with FIG. 1, an analogue orcontinuous value current splitting may be provided. In FIG. 3, thiscould be provided by removing all switching transistors except T1 andT8. The base voltage of these two transistors T1 and T8 could then becontrolled to achieve the desired current splitting portions. If thebase control voltages V_(B1) applied to the transistors T1 and T8 arethe same, an equal signal current portion flows through the transistorsT1 and T8. If one of the base control voltages of the transistors T1 orT8 is lowered, a greater signal current portion will flow through theother transistor and hence through the other output branch.

FIG. 4 shows another implementation of the low-noise amplifier accordingto the second preferred embodiment. In the present case, the transistorsT1 to T8 are replaced by corresponding transistor pairs P1 to P3,wherein one transistor of the transistor pair is connected to the firstoutput branch and controlled by the corresponding switching elements C1to C3 and C 1 to C 3, and wherein the second transistor of thetransistor pairs P1 to P3 is connected with its collector terminal tothe second output branch and controlled by the corresponding switchingelements C1 to C3 and C 1 to C 3 allocated to the second output branch.Both transistors of each transistor pair P1 to P3 are connected at theiremitter terminals. The emitter terminals of the transistors of thetransistor pairs P1 to P3 are connected to a corresponding pair oftransistors T91 and T101, T92 and T102, T93 and T103, wherein the inputvoltage V_(IN1) is supplied to the base terminal of one transistor ofthe transistor pairs, and the input voltage V_(IN2) is supplied to thebase terminal of the other transistor of the transistor pairs.

According to the arrangement shown in FIG. 4, one of the transistors ofthe transistor pairs P1 to P3 is in the non-conducting state and theother one is in the conducting state, such that the corresponding partof the output current is either supplied to the first output branch orsupplied to the second output branch. Thereby, the output currentsupplied to the operated output branch can be controlled by theswitching elements C1 to C3 and C 1 to C 3 to thereby adjust the gain ofthe low-noise amplifier, similar to the first embodiment. In the case ofthe maximum gain, the entire signal current is supplied to theoperational output branch. By switching or steering a part of the signalcurrent to the non-operational output, the gain can be lowered. In thecase shown in FIG. 4, the input transistors T91 to T93 and T101 to T103are divided into three parts and the signal current of these individualtransistors is controlled by the differential transistor pairs P1 to P3.The first input signal V_(IN1) is supplied to the base terminals of thetransistors T91 to T93, and the second input signal V_(IN2) is suppliedto the base terminals of the transistors T101 to T103.

In summary, a method and circuit arrangement for adjusting a gain isdescribed, wherein said circuit arrangement comprises at least a firstoutput branch connected to a first load and a second output branchconnected to a second load. The gain control function is realized basedon a current splitting, wherein a non-operated output branch is used asa kind of dummy branch for receiving a part of the output current. Thus,only as many output branches as there are outputs are required toimplement a gain control based on splitting. Thereby, a complexity ofthe layout design is reduced and control and biasing of dummy branchesis not required.

It is noted, that the present invention is not restricted to the firstand second embodiments and mobile communication systems described aboveand can be applied to any circuit arrangement in any system, where anoperational output branch and a non-operational output branch areprovided. The described gain adjusting function may as well be used inbalanced or differential structures where the two input signals have a180 degree phase shift to each other. The number of input transistorscan be increased if more inputs are required. In general, thearrangement of the input stage can be replaced with any suitablestructure which provides the required or desired signal to the switchingstage 20. The range of the controllable gain depends on the number ofparallel differential transistor pairs and can be increased as desired.Additionally, further output branches can be added, e.g. if more thantwo receiving frequency bands are provided. Hence, the number of inputsand outputs must not be equal. The bipolar transistors can be replacedby any type of transistor or other suitable switching elements. Thus,the present invention may vary within the scope of the attached claims.

1. A method, comprising: providing a circuit arrangement including aplurality of output branches, wherein each of the plurality of outputbranches is connected to an associated load; providing a plurality ofoperational modes wherein each operational mode corresponds to at leastone load and wherein each load is capable of being either operating ornon-operating; switching a predetermined portion of total current fromat least one of the operating loads to another one of the non-operatingloads; adjusting a gain in at least one of the plurality of theoperating modes by changing the predetermined portion of total current.2. The method according to claim 1, wherein in providing the circuitarrangement, each of the loads is a frequency-selective load.
 3. Themethod according to claim 2, further comprising: determining a number ofreceiving frequency bands, thereby creating a determined number offrequency bands.
 4. The method according to claim 3, wherein providingthe circuit arrangement further includes providing the plurality ofoutput loads based on the determined number of frequency bands.
 5. Themethod according to claim 4, wherein in adjusting the gain in thecircuit arrangement, when the predetermined portion of the total currentis decreased, a remaining portion of the total current is increased inthe non-operating loads.
 6. The method according to claim 5, wherein inproviding the circuit arrangement, at least one of the non-operatingloads of the plurality of loads comprise dummy loads.
 7. The methodaccording to claim 1, wherein the method is performed in a receiver. 8.The method according to claim 1, wherein the method is performed in atransceiver.
 9. The method according to claim 1, wherein the method isperformed in a radio-frequency integrated circuit.
 10. The methodaccording to claim 1, wherein the method is performed in adirect-conversion receiver.
 11. The method according to claim 1, whereinthe method is performed in a mobile terminal.
 12. The method accordingto claim 1, wherein the method is performed in a device that is capableof operating in a wireless communications system.
 13. The methodaccording to claim 1, wherein the method is performed in a devicecapable of operating in a global system for mobile communication (GSM).14. An apparatus, comprising: a plurality of circuit output branches,wherein each of the plurality of circuit output branches is connected toan associated load, and wherein the associated load of the plurality ofcircuit output branches is capable of being either operating ornon-operating; a switching unit configured to switch a predeterminedportion of total current from at least one operating load to at leastone non-operating load, wherein the switching unit is further configuredsuch that when the predetermined portion of the total current isswitched to an associated load, an operating load is created and atleast one other non-operating load is created, wherein each of theoperational modes correspond to at least one associated load of theplurality of circuit output branches; and an adjusting unit configuredto adjust a gain in at least one of the plurality of operational modesby changing the predetermined portion of the circuit current.
 15. Theapparatus according to claim 14, wherein the loads are frequencyselective.
 16. The apparatus according to claim 15, wherein the loadsconnected to the non-operating loads comprise dummy loads.
 17. Theapparatus according to claim 16, wherein a number of associated loads isdetermined by a predetermined number of frequency bands.
 18. Theapparatus according to claim 17, further comprising: a selecting unitconfigured to select a frequency band from a plurality of frequencybands, wherein the apparatus is configured to select an operational modeof the plurality of operational modes based the frequency band selectedby the selecting unit.
 19. The apparatus according to claim 18, whereinthe adjusting unit is further configured to control individual switchingelements so as to provide the predetermined portion of the totalcurrent.
 20. The apparatus according to claim 19, wherein the individualswitching elements are controlled by selectively supplying a controlsignal to control terminals of the individual switching elements. 21.The apparatus according to claim 20, wherein the individual switchingelements are connected in parallel.
 22. The apparatus according to claim21, wherein the individual switching elements are transistorarrangements.
 23. The apparatus according to claim 22, wherein thetransistor arrangements comprises individual transistors.
 24. Theapparatus according to claim 22, wherein the transistor arrangementscomprise differential pairs.
 25. The apparatus according to claim 23,wherein the individual transistors are bi-polar transistors.
 26. Theapparatus according to claim 23, wherein the individual transistors arefield effect transistors.
 27. The apparatus according to claim 19,wherein the apparatus further comprises at least one input stage,wherein the at least one input stage is configured to amplify an inputsignal.
 28. The apparatus according to claim 27, wherein the at leastone input stage comprises a plurality of input stages.
 29. The apparatusaccording to claim 28, wherein the at least one input stage comprises aplurality of transistors.
 30. The apparatus according to claim 14,wherein the apparatus is utilized in a receiver.
 31. The apparatusaccording to claim 14, wherein the apparatus is utilized in atransceiver.
 32. The apparatus according to claim 14, wherein theapparatus is a radio-frequency integrated circuit.
 33. The apparatusaccording to claim 14, wherein the apparatus is utilized in adirect-conversion receiver.
 34. The apparatus according to claim 14,wherein the apparatus is utilized in a mobile terminal.
 35. An apparatusaccording to claim 14, that is configured for use in a wirelesscommunications system.
 36. An apparatus according to claim 14, that isconfigured for use in a global system for mobile communications (GSM).37. A radio frequency part of a mobile terminal, comprising: a pluralityof output branches, wherein each of the plurality of output branches isconnected to an associated load and each load is associated with one ofa plurality of operational modes; a switching unit configured to switcha predetermined portion of a total current to one of associated loadsbased on a selected operational mode; and an adjusting unit configuredto adjust a gain of the radio frequency part in at least one of theplurality of operational modes by changing the predetermined portion ofthe current, wherein the receiving portion is further configured tooperate in one of the plurality of operational modes, and configuredsuch that when the at least one load is operated, remaining loads arenot operated, and wherein at least one of the non-operating loadscomprise dummy loads.
 38. The radio frequency part according to claim37, wherein the associated loads are frequency selective.
 39. The radiofrequency part according to claim 38, wherein the adjusting unit isfurther configured to control individual switching elements so as toprovide the predetermined portion of the toal current.
 40. An amplifier,comprising: a plurality of circuit output branches, wherein each of theplurality of circuit output branches is connected to an associated load;a switching unit configured to switch a predetermined portion of a totalcurrent to at least one associated load; wherein the apparatus isconfigurable to operate in a plurality of operational modes, the numberof the operational modes is determined by a number of the plurality ofassociated loads; and an adjusting unit configured to adjust a gain ofthe amplifier in at least one of the plurality of operational modes bychanging the predetermined portion of the total current.
 41. Theamplifier according to claim 40, wherein the loads are frequencyselective.
 42. The amplifier according to claim 41, wherein theadjusting unit is further configured to control individual switchingelements so as to provide the predetermined portion of the totalcurrent.
 43. An apparatus comprising: a plurality of circuit outputbranches, wherein each of the plurality of circuit output branches isconnected to an associated load; a switching means for switching apredetermined portion of a total current to at least one associated loadfrom at least one other associated load; an operating mode determiningmeans for determining an operational mode of a predetermined pluralityof operational modes, wherein the number of the operational modes isdetermined by a number of the associated loads; and an adjusting meansfor adjusting a gain of the apparatus in at least one of the pluralityof operational modes by changing the predetermined portion of the totalcurrent.
 44. The apparatus according to claim 43, wherein the loads arefrequency selective.
 45. The apparatus according to claim 44, whereinthe adjusting means is further configured for controlling individualswitching elements and providing the predetermined portion of the totalcurrent.
 46. A method, comprising: providing a circuit arrangement,wherein the circuit arrangement includes a plurality of output branchesand each of the plurality of output branches is connected to anassociated load; receiving by the circuit arrangement, a signal;selecting an operational mode from a predetermined plurality ofoperational modes based on a frequency of the received signal; operatingat least one associated load based on the selected operational mode,thereby providing an operating load, wherein at least one otherassociated load comprise a non-operating load; switching a predeterminedportion of total current to the operating load from the at least onenon-operating load; and adjusting a gain of the circuit arrangement bychanging the predetermined portion of branch current.
 47. The methodaccording to claim 46, wherein in providing the circuit arrangement,each of the loads is a frequency-selective load.
 48. The methodaccording to claim 47, wherein in adjusting the gain of the circuitarrangement, when the predetermined portion of the total current isdecreased, a remaining portion of the total current is increased in atleast one associated load.